Heat-assisted styling of keratinous fibers (e.g., human hair), particularly using blow dryers, hair straighteners (flat irons), curling devices, heated comb, heated brush (with or without a rotating drum), or other heating means (each of which may be referred to herein as a “Hot Tool”), is prevalent amongst consumers. Unfortunately, heat-assisted styling can dry out and damage hair by subjecting the hair to too much heat. For example, hair can become over dried by holding a blow dryer too close to the hair, or by holding a Hot Tool too long at a particular spot of the hair. The overheating causes moisture to evaporate or be driven out of the hair so that the hair becomes brittle and more susceptible to cracking. In addition, overheating in heat styling can cause physical damage to the hair, particularly by raising the cuticles and/or creating blisters on individual hair fibers, thus causing increased friction between the hair fibers, making it more difficult to comb, requiring increased force to comb the hair, which in turn can wear the outer surface of the hair and cause cracks and breaks in the hair. For years, researchers assumed that human hair was similar in temperature based properties as wool as both are composed of the keratin protein. Recent research reveals that hair exhibits the following characteristics in response to heating:
Stage 1—at or below about 150° C. (302° F.), loosely bound water and tightly bound water is lost or evaporated from the hair.
Stage 2—at between about 160° C. and 175° C. (320° F.-347° F.), hair undergoes a glass transition phase—the hair begins to flow as hot glass would. At this glass transition temperature, plastic deformation of the hair is possible. In a ‘normal’ hydrated state, hair is elastic and can stretch and return back to its original length. Hair exhibits temporary plasticity which is why styles like curls, and twist outs/knot outs can occur. However, at this glass transition temperature, the plasticity of hair is not temporary. Upon cooling, the hair may return to a “normal looking” state, but the hair shaft has been damaged.
Stage 3—at between about 215° C. and 235° C. (419° F.-455° F.), the keratin, which is present in all hair as a natural alpha helix (α-helix), melts, thereby leaving the hair in a permanently damaged state.
Currently, styling of hair is done using tools emitting relatively high heat operating at temperatures over 300° F. to achieve said glass transition/transformation temperature, causing heat damage to hair in the process of styling. When using heat to style hair (or other keratinous fibers), the required temperature to reach a glass transition temperature is proportional to the water saturation or moisture content (i.e., water content) of the keratin fibers. As the water saturation or moisture content increases, the temperature that is required to reach a glass transition temperature decreases. As such, it would be advantageous to use the lowest possible temperature at which styling of the keratinous fibers can be achieved in order to prevent undesirable heat damage, which occurs at temperatures above 300° F., by temporarily increasing the humidity or moisture level in hair.
Persons having naturally curly or wavy hair often desire to alternate, at will, between having a curly or straight (i.e., non-curly) hair style configuration. There is a growing demand for products that can safely and temporarily remove some or all of the natural curl from the hair while at the same time provide the consumer with versatility in styling the hair.
Hair styling or hair setting compositions are widely used by consumers in the cosmetic industry to retain a particular shape or style of the hair. Hair styling compositions can assist in manipulating or styling the hair, providing temporary benefits in holding the shape of the hairstyle (fixing) and/or maintaining the shine or appearance (grooming, restyling) of the hair, e.g., in the evening, during the day, between hair washing periods, or between subsequent hair setting procedures. The inherent problem encountered in hair setting is the natural tendency of the hair to return to its natural shape. For example, the styled or set hair returns to its natural shape almost immediately if moistened. Likewise, high humidity conditions accelerate the tendency of the hair to return to its natural shape. When the hair returns to its natural shape, getting it back to its setting requires repeating the process of styling the hair or a part of, also known as “touching up the hair”. Intensive efforts have been directed toward providing a hair set with sufficient holding power to maintain the designed hair style until at least the next shampoo, and, therefore, giving the styled hair set a degree of permanency. Therefore, investigators have sought to delay the combined action of natural forces and moisture that causes the hair to return to its original state by applying solutions containing naturally-occurring or synthetic polymers after the hair is shaped into a desired configuration. When applied to the shaped hair from aqueous or aqueous/alcoholic solutions (setting lotions), the polymers leave a film on the hair, after drying, to help maintain the hair in the previously shaped configuration. The polymeric film promotes cohesion and gives stability to the hair set to maintain the hold of the hair set. The principal objective of a setting lotion is to cover the previously styled hair with an invisible polymeric film that will give the styled hair a degree of rigidity and protect the hair style against wind and humidity. A problem created by the methods described is the weighing down of hair by the film covering the hair, creating less movement of hair and/or rigidity which are not desired by consumers.
The art of temporarily removing the natural curl from naturally curly hair was practiced, in the early days, by applying a pomade to the hair and then straightening the curl by combing the pomade coated hair, under tension, using a heated metal comb, a process commonly referred to as “pressing.” Although pressing left the hair shiny, silky and temporarily straightened, the process was cumbersome and caused hair damage from excessive heating. The pomades were cosmetically unaesthetic greases and difficult to remove from the hair. Additionally, the metal combs were heated, either electrically or on a stove, to relatively high temperatures, which posed the risk of burning the unprotected skin and scalp or of singeing the hair. More recently, some progress was made using a hair ironing process employing oily lotions and electrical variable heating devices, known as flat hair irons, and hair irons, some of which are combination hair straightener and curling irons, that can be controllably heated. However, the configuration of hair that has been temporarily straightened by these procedures reverts to its natural curly or wavy configuration readily on exposure to humidity, or perspiration, and especially upon washing the hair, as well as the damage caused by the use of these tools at temperatures over about 300° F. still renders the process as not completely satisfactory.
Permanent waving and straightening of hair are common techniques for beautifying hair or fur by permanently forming or setting the hair or fur into a desired configuration. Various techniques have been practiced for many years in the hair and fur industries, such as in hair salons, and in the home practiced by an individual. Hair and fur is comprised of keratin, which is a polyamide cross-linked by disulfide bonds. The disulfide bonds are responsible for the hair or fur being maintained in a particular configuration. In a conventional hair waving or straightening process, the hair is first softened or relaxed by breaking the disulfide bonds in the keratin with a reducing agent and then hardening the hair or fur in the desired configuration by stopping the reduction reaction and restoring or reforming disulfide bonds by applying an oxidizing agent, generally referred to in the art as a neutralizer.
A “Brazilian” hair straightening treatment has been described that requires the use of a formaldehyde solution in conjunction with a heated flat iron set at a temperature of about 232° C. (449.6° F.), to achieve temporary hair straightening with some resistance to reversion. In this process, solutions of formaldehyde (1.5% to 5%) are used which straighten the hair, which lasts through about two to about three shampoo sessions, or about four weeks, before having to repeat the straightening process. Formaldehyde is known to form cross-links among protein end groups to create a stable, complex matrix. For example, formaldehyde can form cross-links between amide, amino, and tyrosine groups, S—CH2-NH cross-links between N-terminal cysteine and amine groups, NH—CH2-NH cross-links between amine groups, and S—CH2-S cross-links. A variation of this procedure has been used in which the hair is first swollen with a composition, referred to in the trade as a dilator, having a pH of about 8.5, rinsed, then treated with a “no-frizz” lotion containing 0.2% formaldehyde, along with a thermal protector lotion containing silicones, and the hair is then blow dried and flat ironed. The hair treated in this manner required repeating the treatment process weekly to progressively attain some level of discernible straightening over a period of four consecutive weeks. Upon stopping usage of the procedure, however, the configuration of the hair reverts to its original wavy or curly pattern after two to three shampooings.
Cross-links produced by formaldehyde are not stable to acid or alkaline hydrolysis, and in aqueous solution, formaldehyde undesirably forms methylene glycol and can react with oxygen to produce formic acid. Additionally, exposure to formaldehyde solutions raises health concerns to the users and practitioners, because formaldehyde generally is presumed to be a carcinogen (i.e., causes cancer), and can cause contact dermatitis. Thus, a formaldehyde-containing solution is toxicologically unacceptable and, in many countries, including Brazil, the amount permitted to be present in hair and skin care products topically applied to humans is controlled and amounts exceeding the allowable level are prohibited. While hair straightened by the foregoing Brazilian processes was silky, straight and shiny, the amount of formaldehyde used exceeds the permissible amount of 0.1% free formaldehyde in cosmetics in Brazil, making it cosmetically undesirable. In Canada the Brazilian treatment was banned by Canadian health authorities in October, 2010. Another concern for users is that the extremely high heat used in the process as well as the chemicals used causes damage to hair, and many users are unhappy with their long term results using this process. The commercial success of the Brazilian treatment has created a great demand for flat irons working at higher temperatures of up to 232° C. (449° F.), shifting the market and getting most of the flat irons made to reach this high heat, keratin melting, and hair damaging temperatures.
Conventional chemical relaxers (hair straighteners) that are formulated to remove substantially all natural curl from the hair are well known in the art and typically contain inorganic or organic bases that convert the disulfide bonds of cystine in hair to stable, irreversible crosslinks of primarily lanthionine by the action of hydroxide ion. These lanthionizing chemical relaxers generally are highly alkaline, typically in the range of about pH 12 to about pH 14 and, and typically produce a straight textural configuration that is substantially permanent (i.e., irreversible). Some consumers, however, do not wish to be committed to just one texture and some are increasingly hesitant to risk exposing their hair and scalp to possible damage from such high alkalinity. As such, an alternative to lanthionization relaxers is a chemical keratin reduction-oxidation relaxer process. Conventional commercial reduction-oxidation processes typically reduce the disulfide bonds in the hair with thiol salts, usually ammonium thioglycolate in a viscous medium at an alkalinity typically in the range of about 9 to about 9.5. The reduced hair is mechanically straightened with combing, and then oxidized with hydrogen peroxide or sodium bromate to restore the disulfide bonds in the new straightened configuration. The straightening effect lasts through about three to four shampooings, but generally provides a less permanent straightening effect than that achieved by lanthionization, which damages hair by destroying the natural cysteine groups or disulfide bonds that account for hair's strength, and most of its toughness and abrasion resistance. One attempt to avoid conventional lanthionizing chemical relaxer was a multiple-step, heat-assisted, reduction-oxidation process. The hair was chemically reduced with an ammonium thioglycolate cream composition, shampooed, dried with a hair dryer, mechanically straightened with a heated flat iron set at a temperature of about 200° C., then chemically oxidized with a sodium bromate or hydrogen peroxide lotion, dried with a hair drier, and again mechanically straightened with the heated flat iron. This process, however, was tediously long, taking between four and six hours to complete, and chemical damage as well as high heat damage was not avoided.
Various methods are used to measure the efficacy of a hair-styling composition. One method commonly employed to objectively test the efficacy of hair styling compositions involves measuring curl retention under humid conditions. Another method involves semi-permanent hair straightening using a flat iron followed by several wash-out steps. Additional methods of subjective evaluation may be employed that include, for examples: visual and tactile sensory methods (e.g., by visual examination and touching) for characteristics such as appearance (shine, cleanliness, naturalness of appearance and texture), feel (stiffness, tackiness, softness), curl memory (bounce, and restylability), straightness memory (flatness), ease of combing and brushing the hair, residue (flaking), static, smoothness, and the like. Also of importance are the aesthetic characteristics and appearance provided by hair styling compositions before, during, and after application to hair. The product viscosity should be non-runny to avoid dripping during application. The product should be easy to spread, have a smooth texture, a non-tacky feel, and be able to dry relatively quickly on the hair.
Providing hair styling compositions that exhibit good high humidity curl and/or straightness retention while maintaining desirable subjective properties, e.g., smooth texture, curl memory, bounce, naturalness of appearance, etc., has been difficult to achieve with conventional hair-setting compositions. If left untreated, hair often becomes tangled when wet and/or dry such that combing and brushing of the hair is difficult. Furthermore, hair frequently exhibits poor electrostatic properties such that it is susceptible to “scattering”, especially in low humidity environments. In addition, conventional hair straightening and conditioning compositions generally contain man-made chemicals that often leave the hair undesirably harsh, dull, and dry. In addition, conventional hair straightening involves high heat temperatures over 300° F., which undesirably damages hair and other keratinous fibers.
There is an ongoing need and desire, therefore, for cosmetically acceptable compositions and convenient practical processes that temporarily remove some or all of the natural curl from naturally curly hair, and provide some resistance to curl reversion on exposure to humidity, perspiration, or washing, and yet provide the user with versatility in alternating between a straight or curly hairstyle.
To address the above and other shortcomings, below are provided compositions, kits, tools and/or methods for styling hair and other keratin-based fibers without the use of temperatures above about 300° F., or with no heat at all, which are capable of providing, among other things, high humidity curl and/or straightness retention, versatility in alternating between straight or curly hairstyles from wash to wash so the end user would not need to touch up the hair between washes, but have the ability to change hair style from curly to straight and vice versa at will with hair washing/shampooing as the reset event. The example embodiments below include compositions and methods for achieving high humidity curl and/straightness retention without coating the hair with film, thereby achieving a benefit of hair feeling weightless. The example embodiments may overcome one or more of the limitations and disadvantages in the art of hair care by providing thermal hair straightening and conditioning compositions that can be applied before, and during thermal straightening to render the hair smoother, shinier, softer, and more manageable, to minimize static charge, tangling, and scattering of the hair, such that the hair becomes smooth and straight after application. Further, the styling compositions and processes disclosed herein avoid the deleterious action that can be caused by conventional high heat treatments or highly alkaline lanthionization chemical hair relaxer processes, as readily determined by measured changes in the physical, mechanical integrity of the keratin fibers. Measurable changes in the integrity of the hair include desirable changes in tensile strength properties (increased about 5% to 20%), elasticity, porosity, cuticle erosion, fiber breakage, wet and dry combing force and the like, as well as changes in discernible subjective properties, i.e., tactile feel, and visible sheen or appearance.
As a result, the styling compositions and methods may provide substantially increased body to keratinous fibers, especially human hair; provide better uptake of protein monomers or polymers onto the hair; provide a polymer coating with less flaking; provide a more complete attachment of the resulting polymer to the hair, better protect the hair against uptake of humidity; strengthen damaged hair; resist removal through at least several shampooings; prevent leach out of hair colors; provide for higher loading of polymer into and onto the hair and, therefore, better set retention; protect the hair against thermal damage by completely avoiding high heat damaging temperatures typically used for styling hair (i.e., above about 300° F.) and better resist hair uptake of atmospheric contaminants.